The invention concerns an apparatus for the fermentative conversion of a nutrient mixture by means of microorganisms in the presence of a gas containing oxygen. Apparatuses of this sort are employed in the production of proteins.
It is necessary, with such processes, to attain a highly effective oxygen input into the nutrient mixture since a corresponding reduction of capital expenditure/operational costs as compared with the amount of protein obtained may then be attained. As is known, microorganisms are employed in processes for the fermentative conversion of nutrient mixture that in their aqueous phase have a water content of 90% or more. The amount of oxygen necessary for the fermentative transformation is added in the form of air. The fermentation process is essentially dependent on the distribution, that is to say the rotation and mixing of all reactants and their diffusion through the phase interfaces. An effort is made to hold or to attain a high transfer rate. In fermentation, a definite temperature must be maintained as the optimum growth temperature.
Nutrient mixtures contain the elements necessary for the production of proteins, the elements being in the form of chemical compounds that are either water soluble, emulsible or dispersive.
As a source of carbon, the following may be used:
Methanol PA1 Ethanol PA1 Paraffins PA1 Gas oil PA1 Methane PA1 Glucose and other sugars PA1 Starch PA1 Cellulose PA1 Nh.sub.3 PA1 Hno.sub.3 and its salts PA1 Urea PA1 Hydrazine PA1 H.sub.3 po.sub.4 PA1 H.sub.2 so.sub.4 PA1 NaOH and their salts PA1 Koh PA1 Ca(OH).sub.2 PA1 MgSO.sub.4 PA1 FeSO.sub.4 PA1 and/or ZnSO.sub.4 PA1 Bacteria of the following typical strains: PA1 As well as yeasts of families such as
As a source of nitrogen:
The following inorganic substrates can be added to the nutrient mixtures:
In addition, the following trace elements are added to the nutrient mixture:
The following micoorganisms are used:
Micrococcus PA2 Pseudomanas PA2 Chrombacterium PA2 Flavobacterium PA2 Hansenula PA2 Torulopsis PA2 Candida
There are processes known in which air is introduced by a distribution system into the nutrient mixture in aqueous phase and this aerated mixture is further vigorously mixed by an agitator.
Fermentation processes take place in so-called fermenters. These are large vessels or columns, the greatest part of whose contents is aqueous nutrient. The fermentation, assisted by microorganisms, is carried out by the so-called submerged culture with the addition of air or oxygen. The thorough intermixing of the reaction components is effected mechanically by stirrers, pneumatically by air disbribution or in loop reactors with aeration by jets or tubes or via the so-called airlift fermenters or, hydrodynamically with the aid of packing material.
Fermentation in the conventional stirred tanks takes place in a satisfactory manner as far as product quality and growth characteristics are concerned. The expenditure of energy is, of course, considerable since a large part of the energy fed into the stirring apparatus is transferred to the vessel walls in the form of heat, without having been used for the process.
Fermentation in the various types of airlift fermenters have a much more favorable exploitation of energy but they only have a sufficient utilization of oxygen when they attain a certain height, approx. 20 m. or more.
Fermentation in loop reactors with nozzles and tube gasification has positive results and is satisfactory in comparison with other known types of fermenters. Circulation rates of a 100 times per hour and more are attained. Problems arise when foaming occurs at high protein concentrations, resulting in occasional work stoppages.